Bacillus lehensis-an alkali-tolerant bacterium isolated from cassava starch wastewater: optimization of parameters for cyclodextrin glycosyltransferase production

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Application of crude xylanase from Bacillus licheniformis 77-2 to the bleaching of eucalyptus Kraft pulp

Alkalophilic Bacillus licheniformis 77-2 produced an extracellular alkali-tolerant xylanase with negligible cellulase activity in medium containing corn straw. The effectiveness of crude xylanase on treatment of eucalyptus Kraft pulp was evaluated. A biobleaching experiment was carried out to compare the chlorine saving with pulp treated and untreated by the enzyme. Two-stage bleaching was employed, using a ClO2 chlorination and NaOH extraction (DE sequence). With the enzymatic treatment, in order to obtain the same value of Kappa number and brightness, respectively 28.5 and 30% less ClO2 was required in comparison to the enzymatically untreated samples.

两株耐碱性木聚糖酶产生菌的筛选及产酶条件研究

本文主要研究了从造纸厂碱性土壤中筛选得到的，能够产生耐碱木聚糖酶的两株放线菌X24-14和X15-17。通过16 S rRNA基因序列分析并结合菌株的形态特征以及生理生化特性，初步认为菌株X15-17为拟诺卡氏菌属（Nocardiopsis）的一个潜在新种；菌株X24-14为纤维化纤维菌（Cellulosimicrobium cellulans）。 在此基础上探索了菌株X24-14和菌株X15-17所产木聚糖酶的基本酶学性质。研究发现，两株菌所产的木聚糖酶的耐碱性均较强： 1）菌株X24-14所产的木聚糖酶，在pH 4.2～9.4的范围内能维持较高的活力，pH 9.4条件下，仍能保持80％的酶活力；2）菌株X15-17所产的木聚糖酶在pH 4.0～9.0的范围内能维持较高的活力，pH 9.0条件下，仍能保持80％的酶活力；3）两株菌所产的木聚糖酶均具有较好的pH稳定性，在pH 2.0～11.0范围内稳定，pH 11.0、4 ℃条件下处理24 h仍具有75％的活力。 本文还重点研究了菌株X24-14在不同培养基成分及不同培养条件下的产酶情况，确定了其适宜的产酶条件。结果显示，菌株X24-14的最适碳源为麸皮；最适氮源为蛋白胨；最适产酶pH为pH 8.5。菌株X24-14适宜的产酶条件为：麸皮60 g/L，蛋白胨10 g/L，K2HPO4 7.0 g/L，pH 8.5，接种量为5％，37 ℃，200 r/min发酵培养108 h。 Two strains of actinomycetes, X24-14 and X15-17, which produced alkali-tolerant xylanase were screened from the soil samples collected from a pulp mill in china. Based on the morphological, physiochemical characteristics and 16S rRNA sequence, X24-14 was priminarily identified as cellulosimicrobium cellulans ; X15-17 was priminarily identified as a new species of Nocardiopsis. The investigation examined the enzyme activities which produced by X24-14 and X15-17 under different pH and different temperatures. The results showed that : 1）The xylanase from X24-14 had characteristic of alkali-tolerance: It remains 80% relative activity at pH ranges between pH 4.2 and pH 9.4 under 50℃. 2)The xylanase from X15-17 also showed characteristic of alkali-tolerance, it remains 80% relative activity at pH ranges between pH 4.0and pH 9.0 under 50℃. 3）The xylanase from the two strains showed alkali-stable characteristics. They were stable at pH ranges between pH 2.0 and pH 11.0, showing 75% of its maximal activity remaining under 24 hours of treatment at 4℃. We also studied the effect of different growth conditions: carbon source, nitrogen sources, inoculum size, and initial pH on the production of xylanase of strain X24-14. The results showed that :The optimal carbon source was wheat bran; The optima nitrogen source was peptone; The maximum xylanase activity was achieved in the medium containing 60 g/L wheat bran, 10 g/L peptone, 7 g/L K2HPO4, inoculum size 5% and pH 8.5, under 37℃ in 108 h.

松嫩平原南部主要耐盐碱植物群落生物生态学机制的初步探讨

本文采用野外调查分析和室内室验相结合的方法，初步探讨了松嫩平原南部主要耐盐碱植物群落形成和分布的生物生态学机制，得出如下结论： （1）土壤盐碱含量是决定耐盐碱植物群落组成和分布的主导因素。当土壤盐碱含量逐渐增大时，依次分布着虎尾草、羊草、星星草和碱蓬植物群落，并且这些植物群落的种类组成不同。虎尾草、羊草的生态幅度较广，星星草和碱蓬生态幅度较窄。 （2）在野外不同土壤条件下采集的星星草，体内脯氨酸含量有规律地变化。说明在盐碱生境下，植物通过调节体内某些生理反应来适应盐碱生境。 （3）在实验室控制条件下，研究植物对盐碱因素的反应，碱蓬、星星草、虎尾草在生理指标上表现出对盐碱生境的适应性依次减弱。这种适应特性的不同是植物群落形成和分布的主导因素。在盐碱生境下，碱蓬的发芽势、发芽率、呼吸强度、ATP含量和生长量普遍高于其它植物，有一定盐碱（500PPm Na2CO3）存在时，生命活动受促进，在较宽盐碱浓度范围（低于3000PPm Na2CO3）内，受抑制不显著，且以稀盐机制避盐，所以在高含量盐碱土上，碱蓬竞争力强，形成耐盐碱性强的碱蓬群落。星星草在一定盐碱(250 PPm Na2CO3)存在时，生命活动得到促进，在较低浓度的盐碱溶液（1000PPm Na2CO3）中，生命活动被明显抑制，且星星草以拒盐机制躲避盐的伤害，所以在较低含量的盐碱土上，生长良好，形成耐盐碱的群落，该群落耐盐碱性低于碱蓬群落。由于碱蓬和星星草生命活动要求一定量的盐碱，所以在盐碱含量很低的土壤上，生长不好，生态幅度较窄。虎尾草在盐碱存在下，生命活动受到抑制，所以虎尾草只有在盐碱含量很低的土壤上生长良好，形成虎尾草群落。由于在很宽的盐碱浓度范围内，虎尾草受抑制作用不明显，所以虎尾草在其它许多耐盐碱植物群落中，作为伴生种存在，生态幅度较宽。

耐酸产甲烷菌的分离及其复合菌剂的研究

本文从成都龙泉垃圾填埋场和宜宾造纸厂分离到耐酸性能优良的高温产甲烷菌RY3和中温产甲烷菌SH4，并将其与实验室现有的利用不同底物的产甲烷菌配伍组合成了复合菌剂。采用活性污泥作为固体附着物，研制出了固体产甲烷菌复合菌剂。 菌株RY3的pH耐受范围为5.5～10.5，最适生长pH 6.0～8.0。菌株RY3为革兰氏阳性，长杆状，多数单生，不运动；菌落浅黄色，形状近圆形；利用H2+CO2或甲酸盐作为唯一碳源生长，不利用乙酸盐，对氯霉素非常敏感。该菌最适生长温度为55℃～65℃，最适NaCl浓度为0～2%。根据形态和生理生化特性及16S rDNA序列分析将其初步定为热自养甲烷热杆菌（Methanothermobacter thermautotrophicus）。添加RY3菌液与仅添加厌氧污泥作为接种物相比一周内可使达到最大产甲烷速率所需时间缩短三分之二，甲烷总产量提高约1.8倍。菌株SH4的生长pH范围5.5～9.5，其对酸碱具有良好的适应性，培养3天后，在初始pH值为6.0～8.0的培养基中甲烷产量相差不大，且基本达到最大产量。SH4革兰氏染色阳性，短杆状，多数单生，不运动；菌落近圆形，微黄；利用H2+CO2或甲酸盐作为唯一碳源生长，不利用乙酸盐，对氯霉素非常敏感。SH4最适生长pH 为7.0，最适生长温度为35℃，最适NaCl浓度为0～1.5%。实验表明，添加SH4菌液与仅添加厌氧污泥作为接种物相比可使产甲烷启动时间缩短三分之一，甲烷总产量亦有大幅提高。从形态和生理生化特征以及16S rDNA序列分析表明SH4为嗜树木甲烷短杆菌（Methanobrevibacter arboriphilus）。 以活性污泥为附着物，与培养基和菌种经搅拌后厌氧发酵可得产甲烷菌固体复合菌剂。固体复合菌剂的pH耐受范围为5.5～9.5，温度耐受范围为15℃～65℃，表明其对环境的适应性较强。以猪粪为底物进行厌氧发酵，接种复合菌剂进行试验，以接种实验室长期富集的产甲烷厌氧污泥作为对照，在20℃时，发酵甲烷浓度与对照基本一致，但每日产气量优于对照，第15天时接种复合菌剂的发酵瓶每日产气量是对照的1.59倍；50℃时达到最大甲烷含量所需时间比对照缩短三分之二，三周内总产气量约为对照的2.7倍，甲烷总产量约为2.8倍。以不加接种物为对照，接种复合菌剂20℃时发酵甲烷含量达到50%约需2周，对照2周内甲烷含量最高仅为4.3%；50℃时接种复合菌剂发酵仅需约1周甲烷含量便可达50%，对照则至少需要2周。 In this paper, high-temperature Methanogen RY3 and middle-temperature SH4 were isolated from Chengdu Longquan refuse landfill and Yibin paper mill. They could be used to make compound inoculum that producing methane with the existing Methanogens utilized different substrate. With using anaerobic activated sludge be solid fixture, the process had been designed to produce solid compound inoculum. Strain RY3 possessed excellent capacity of acid and alkali-tolerant. The pH-tolerant scale of RY3 was 5.5～10.5 and its optimum pH value for growth was 6.0～8.0. RY3 was G+, long-rod shape, monothetic and nonmotile, the colony was pale yellow with suborbicular-shape. Formate or H2+CO2 but not acetate was utilized by RY3 as sole C-source, and it was very sensitive to chloramphenicol. Besides, strain RY3 grew fastest at 55℃～65 and 0℃～2% NaCl. Characteristics of modality and physiology with sequence analysis of the 16s rDNA gene of strain RY3 preliminarily showed that it was Methanothermobacter thermautotrophicus. The experiments indicated that the time which began to produce methane with the highest velocity could be shortened two third by adding RY3 in one week, and the total methane production also was 1.8 times than before. Strain SH4 possessed wide scale of growing pH（5.5～9.5）and excellent ability of acclimatizing itself to acid-alkali. The methane production had no apparent difference among those cultivated in different initial pH（6.0～8.0）after three days and equaled to the maximum production basically. Cells of SH4 were G+, short-rod sharp, monothetic and nonmotile. The colony was pale yellow with suborbicular-shape. Formate or H2+CO2 but not acetate was utilized by SH4 as sole C-source, and it was very sensitive to chloramphenicol. Besides, it grew fastest at pH 7.0，55 ℃～65 and 0℃～2% NaCl concentration. The experiment indicated the time that began to produce methane could be shortening one third by adding SH4. And the total methane production also rose apparently. Characteristic of modality and physiology with sequence analysis of the 16S rDNA gene of strain SH4 demonstrated it was Methanobrevibacter arboriphilus. The activated sludge was utilized as fixture, mixed with culture medium and inocolum, that the solid compound inoculum could be produced by anaerobic fermentation. The compound inoculum could grow between pH 5.5～9.5, 15℃～65. It demonstrated the compound inoculum ha℃ve great ability of adapting to circumstance. In the experiment that making pig manure be substrate and taking the anaerobic sludge producing methane that cultured in long term in laboratory to be comparison, the concentration of methane in fermentation added compound inoculum almost equal to the comparison at 20℃, but the volume of gas production could be a little higher. The gas production everyday inoculated compound inoculum was 1.59 times to comparison. The time that the concentration of methane to maximum could be shortening by two third by adding compound inoculum, and the total gas production was 2.7 times to comprison while the total methane production was 2.8 times. If take the no inoculum be the comprasion, anaerobic fermentation added compound inoculum made the concentration of methane to 50% in 2 weeks but the comparison only to 4.3% at 20℃. The time that the concentration of methane to 50% by adding compound inoculum only need 1 week, but the comparison need 2 weeks at 50℃.

Revegetation strategies for bauxite refinery residue: A case study of Alcan Gove in Northern Territory, Australia

Alumina extraction from bauxite ore with strong alkali produces waste bauxite refinery residue consisting of residue sand and red mud. The amount and composition of refinery residue depend on the purity of the bauxite ore and extraction conditions, and differs between refineries. The refinery residue is usually stored in engineered disposal areas that eventually have to be revegetated. This is challenging because of the alkaline and sodic nature of the residue. At Alcan Gove's bauxite refinery in Gove, Northern Territory, Australia, research into revegetation of bauxite residue has been conducted since the mid-1970s. In this review, we discuss approaches taken by Alcan Gove to achieve revegetation outcomes (soil capping of refinery residue) on wet-slurry disposal areas. Problems encountered in the past include poor drainage and water logging during the wet season, and salt scalding and capillary rise during the dry season. The amount of available water in the soil capping is the most important determinant of vegetation survival in the seasonally dry climate. Vegetation cover was found to prevent deterioration of the soil cover by minimising capillary rise of alkalinity from the refinery residue. The sodicity and alkalinity of the residue in old impoundments has diminished slightly over the 25 years since it was deposited. However, development of a blocky structure in red mud, presumably due to desiccation, allows root penetration, thereby supplying additional water to salt and alkali-tolerant plant species. This has led to the establishment of an ecosystem that approaches a native woodland.

Sulfur-tolerant NOx storage traps: an infrared and thermodynamic study of the reactions of alkali and alkaline-earth metal sulfates

The sulfur tolerance of a barium-containing NOx storage/reduction trap was investigated using infrared analysis. It was confirmed that barium carbonate could be replaced by barium sulfate by reaction with low concentrations of sulfur dioxide (50 ppm) in the presence of large concentrations of carbon dioxide (10%) at temperatures up to 700 degreesC. These sulfates could at least be partially removed by switching to hydrogen-rich conditions at elevated temperatures. Thermodynamic calculations were used to evaluate the effects of gas composition and temperature on the various reactions of barium sulfate and carbonate under oxidizing and reducing conditions. These calculations clearly showed that if, under a hydrogen-rich atmosphere, carbon dioxide is included as a reactant and barium carbonate as a product then barium sulfate can be removed by reaction with carbon dioxide at a much lower temperature than is possible by decomposition to barium oxide. It was also found that if hydrogen sulfide was included as a product of decomposition of barium sulfate instead of sulfur dioxide then the temperature of reaction could be significantly lowered. Similar calculations were conducted using a selection of other alkaline-earth and alkali metals. In this case calculations were simulated in a gas mixture containing carbon monoxide, hydrogen and carbon dioxide with partial pressures similar to those encountered in real exhausts during switches to rich conditions. The results indicated that there are metals such as lithium and strontium with less stable sulfates than barium, which may also possess sufficient NOx storage capacity to give sulfur-tolerant NOx traps.

The Critical Role of N- and C-Terminal Contact in Protein Stability and Folding of a Family 10 Xylanase under Extreme Conditions

Background: Stabilization strategies adopted by proteins under extreme conditions are very complex and involve various kinds of interactions. Recent studies have shown that a large proportion of proteins have their N- and C-terminal elements in close contact and suggested they play a role in protein folding and stability. However, the biological significance of this contact remains elusive. Methodology: In the present study, we investigate the role of N- and C-terminal residue interaction using a family 10 xylanase (BSX) with a TIM-barrel structure that shows stability under high temperature,alkali pH, and protease and SDS treatment. Based on crystal structure,an aromatic cluster was identified that involves Phe4, Trp6 and Tyr343 holding the Nand C-terminus together; this is a unique and important feature of this protein that might be crucial for folding and stabilityunder poly-extreme conditions. Conclusion: A series of mutants was created to disrupt this aromatic cluster formation and study the loss of stability and function under given conditions. While the deletions of Phe4 resulted in loss of stability, removal of Trp6 and Tyr343 affected in vivo folding and activity. Alanine substitution with Phe4, Trp6 and Tyr343 drastically decreased stability under all parameters studied. Importantly,substitution of Phe4 with Trp increased stability in SDS treatment.Mass spectrometry results of limited proteolysis further demonstrated that the Arg344 residue is highly susceptible to trypsin digestion in sensitive mutants such as DF4, W6A and Y343A, suggesting again that disruption of the Phe4-Trp6-Tyr343 (F-W-Y) cluster destabilizes the N-and C-terminal interaction. Our results underscore the importance of N- and C-terminal contact through aromatic interactions in protein folding and stability under extreme conditions, and these results may be useful to improve the stability of other proteins under suboptimal conditions.

Zeolite from alkali modified kaolin increases NH4+ retention by sandy soil : column experiments

Sandy soils have low water and nutrient retention capabilities so that zeolite soil amendments are used for high value land uses including turf and horticulture to reduce leaching losses of NH4+ fertilisers. MesoLite is a zeolitic material made by caustic treatment of kaolin at 80-95oC. It has a moderately low surface area (9-12m2/g) and very high cation exchange capacity (494 cmol(+)/kg). Laboratory column experiments showed that an addition of 0.4% MesoLite to a sandy soil greatly (90%) reduced leaching of added NH4+ compared to an unamended soil and MesoLite is 11 times more efficient in retaining NH4+ than natural zeolite. Furthermore, NH4+-MesoLite slowly releases NH4+ to soil solution and is likely to be an effective slow release fertiliser.

Social capital in a tolerant society? a response to treasurer Costello’s presentation to the Sydney Institute

On 16 July 2003 the Australian Government’s Treasurer, the Honourable Peter Costello, addressed the Sydney Institute on his vision for a tolerant Australian society. Drawing from Putnam’s research Costello argued that tolerance will flow from an active voluntary sector. However, Costello’s proposed model for a “tolerant” society fails to acknowledge that all behaviour is strategic and that voluntary association based on disinterested action is not possible. Ultimately, Treasurer Costello’s notion of tolerant society fuelled by an active voluntary sector may not lead to his desired end. Indeed, the promotion of voluntary association may contribute to the ongoing exclusion of citizens with low social capital. Amid the dynamism of the modern era some citizens such as ageing workers, slow or ineffective learners and women may be especially at risk. Accordingly, rather than advocating a policy approach that seeks to build inclusiveness through an active voluntary sector this paper recommends a policy approach that explores ways in which to strengthen learning and the wider involvement of individuals through both formal and informal means.

Effect of thermal treatment on adsorption-desorption of ammonia and sulfur dioxide on palygorskite : change of surface acid-alkali properties

Thermally activated Palygorskite (Pg) has been found to be a good adsorbent material for ammonia (NH3) and sulfur dioxide (SO2). This research investigated the effect of thermal treatment on pore structure and surface acid-alkali properties of Pg through the adsorption-desorption of NH3 and SO2. The results showed that, up to 200 °C, the adsorption of NH3 on Pg was significantly higher than SO2. This was due to NH3 being adsorbed in the internal surface of Pg and forming hydrogen bonds (H-bonds) with coordinated water. The increase in thermal treatment temp. from 150 to 550 °C, showed a gradual decrease in the no. of surface acid sites, while the no. of surface alk. sites increased from 200 to 400 °C. The change of surface acidity-alk. sites is due to the collapse of internal channels of Pg and desorption of different types of hydroxyls assocd. with the Pg structure.

Use of a zeolite synthesised from alkali treated kaolin as a K fertiliser : glasshouse experiments on leaching and uptake of K by wheat plants in sandy soil

Zeolite N, a zeolite referred to in earlier publications as MesoLite, is made by caustic reaction of kaolin at temperatures between 80 °C and 95 °C. This material has a very high cation exchange capacity (CEC ≈ 500 meq/100 g). Soil column leaching experiments have shown that K-zeolite N additions greatly reduce leaching of NH4+ fertilisers but the agronomic effectiveness of the retained K+ and NH4+ is unknown. To measure the bioavailability of K in this zeolite, wheat was grown in a glasshouse with K-zeolite N as the K fertiliser in highly-leached and non-leached pots for four weeks and compared with a soluble K fertiliser (KCl). The plants grown in non-leached pots and fertilised with K-zeolite N were slightly larger than those grown with KCl. The elemental compositions in the plants were similar except for Si being significantly more concentrated in the plants supplied with K-zeolite N. Thus K-zeolite N may be an effective K-fertiliser. Plants grown in highly-leached pots were significantly smaller than those grown in non-leached pots. Plants grown in highly-leached pots were severely K deficient as half of the K from both KCl and K-zeolite N was leached from the pots within three days.

Sensor fault-tolerant observer applied in satellite attitude control

The observing failure and feedback instability might happen when the partial sensors of a satellite attitude control system (SACS) go wrong. A fault diagnosis and isolation (FDI) method based on a fault observer is introduced to detect and isolate the fault sensor at first. Based on the FDI result, the object system state-space equation is transformed and divided into a corresponsive triangular canonical form to decouple the normal subsystem from the fault subsystem. And then the KX fault-tolerant observers of the system in different modes are designed and embedded into online monitoring. The outputs of all KX fault-tolerant observers are selected by the control switch process. That can make sense that the SACS is part-observed and in stable when the partial sensors break down. Simulation results demonstrate the effectiveness and superiority of the proposed method.